1. Field of the Invention
The present invention relates to a method and apparatus for forming a thin layer of dry developer, and a developing apparatus using the same.
2. Description of the Prior Art
Conventionally, various types of apparatus have been proposed and put into practice as to a dry type one-component developer apparatus. However, in any of those types, it has been very difficult to form a thin layer of one-component dry developer, so that a relatively thick layer of the developer is used. On the other hand, a recent device for improved sharpness, resolution or the other qualities has necessitated the achievement of a system for forming a thin layer of one-component dry developer.
A method of forming a thin layer of one-component dry developer has been proposed in U.S. Pat. Nos. 4,386,577 and 4,387,664 and this has been put into practice. However, those patents relate to the formation of a thin layer of a magnetic developer, not of a non-magnetic developer. The particles of a magnetic developer must each contain a magnetic material to have magnetic properties. This is disadvantageous since it results in poor image fixing when the developed image is fixed of a transfer material, also in poor reproducibility of color (because on the magnetic material, which is usually black, contained in the developer particles).
Therefore, there has been proposed a method wherein the developer is applied by a cylindrical soft brush made of, for example, beaver fur, or a method wherein the developer is applied by a doctor blade to a developer roller having a textile surface, such as velvet, for formation of a thin non-magnetic developer layer. In the case where the textile brush is used with a resilient material blade, it is possible to regulate the amount of developer applied, but the applied toner layer is not uniform in thickness. Moreover, the blade only rubs the brush so that the developer particles are not charged, resulting in foggy images.